An atmospheric optical phenomenon of snow-covered regions in which the observer appears to be engulfed in a uniformly white glow. Shadows, the horizon, and clouds are not discernible; depth perception and the sense of orientation are lost; and only very dark, nearby objects can be seen. Whiteout occurs over an unbroken snow cover and beneath a uniformly overcast sky when, with the aid of the snowblink effect, the light from the sky is about equal to that from the snow surface. Blowing snow may be an additional cause.